To achieve the objectives of energy saving, high efficiency and small form factor, electronic device requires power supply with higher efficiency. Meanwhile, telecom equipment and servers with higher speed and more storage capacity consume more electricity. As a result, some devices such as DC/DC conversion power supply in these equipments need energy saving design and require lower output voltage and lower power consumption in idle mode. Therefore, power MOSFET with high efficiency, tiny and thin package, low voltage, large current, high conversion rate and intelligent control is developed.
In traditional power semiconductor device, if multiple semiconductor chips are included in an integrated package, then the lead frame may includes multiple separate die paddles for different chips. As shown in FIG. 1, semiconductor device 100 includes multiple MOSFETs 110, 111 and a power control IC 112 respectively connecting to separate die paddles 101 and 102, thus resulting into a big footprint for the device 100. Furthermore, due to separate die paddles 101 and 102, thermal dissipation effect for MOSFETs 110, 111 is not optimized.
FIG. 2 is a cross sectional diagram of a flip chip configuration of a conventional semiconductor device. In semiconductor device 200, a semiconductor chip 210 is stacked on multiple pins 201 through multiple solder bumps 220. In this configuration, the lead frame only consists of multiple pins 201. However, one disadvantage of this configuration is that the semiconductor chip 210 is not exposed out of the plastic package for heat dissipation, therefore this configuration cannot be applied for MOSFETs that require large thermal dissipation capability.
FIG. 3 shows a top view of another flip chip configuration of a conventional semiconductor device. In semiconductor device 300, an electrode (such as gate electrode) of flip chip 310 is connected to a metal bump 302a of a lead 302, while another electrode (such as source electrode) is connected to metal bump 301a on a die paddle 301, as such the plastic packaging materials cannot be completely filled in the notch between chip 310 and die paddle 301. With the current requirement in reducing working voltage of electronic products, power device usually requires DC-DC converter with low voltage, large output current as well as high thermal dissipation capability and high reliability, the improvement in thermal dissipation or reliability of the power semiconductor devices is necessary.